CA2045685C - Method of corrosion protection at pipe junctions - Google Patents
Method of corrosion protection at pipe junctionsInfo
- Publication number
- CA2045685C CA2045685C CA002045685A CA2045685A CA2045685C CA 2045685 C CA2045685 C CA 2045685C CA 002045685 A CA002045685 A CA 002045685A CA 2045685 A CA2045685 A CA 2045685A CA 2045685 C CA2045685 C CA 2045685C
- Authority
- CA
- Canada
- Prior art keywords
- pipe
- temperature
- socket end
- heating
- protective layer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000000034 method Methods 0.000 title claims abstract description 41
- 230000007797 corrosion Effects 0.000 title claims abstract description 25
- 238000005260 corrosion Methods 0.000 title claims abstract description 25
- 238000000576 coating method Methods 0.000 claims abstract description 23
- 238000010438 heat treatment Methods 0.000 claims abstract description 23
- 239000011241 protective layer Substances 0.000 claims abstract description 22
- 230000013011 mating Effects 0.000 claims abstract description 9
- 239000011253 protective coating Substances 0.000 claims abstract description 9
- 239000000463 material Substances 0.000 claims abstract description 8
- 230000000295 complement effect Effects 0.000 claims abstract description 4
- 239000011248 coating agent Substances 0.000 claims description 19
- 229910000831 Steel Inorganic materials 0.000 claims description 11
- 239000010959 steel Substances 0.000 claims description 11
- 238000010791 quenching Methods 0.000 claims description 10
- 239000004033 plastic Substances 0.000 claims description 7
- 229920003023 plastic Polymers 0.000 claims description 7
- 230000005855 radiation Effects 0.000 claims description 7
- 238000001816 cooling Methods 0.000 claims description 6
- 238000005098 hot rolling Methods 0.000 claims description 5
- 230000006698 induction Effects 0.000 claims description 5
- 238000003303 reheating Methods 0.000 claims description 5
- 239000010410 layer Substances 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 238000005422 blasting Methods 0.000 claims description 3
- 230000000171 quenching effect Effects 0.000 claims 9
- 239000010935 stainless steel Substances 0.000 claims 1
- 230000006870 function Effects 0.000 abstract 1
- 239000004698 Polyethylene Substances 0.000 description 7
- -1 polyethylene Polymers 0.000 description 6
- 229920000573 polyethylene Polymers 0.000 description 6
- 238000005096 rolling process Methods 0.000 description 6
- 239000006223 plastic coating Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 230000036760 body temperature Effects 0.000 description 3
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- 239000004568 cement Substances 0.000 description 2
- 239000002674 ointment Substances 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 101100264195 Caenorhabditis elegans app-1 gene Proteins 0.000 description 1
- 239000004593 Epoxy Substances 0.000 description 1
- 241000920340 Pion Species 0.000 description 1
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 238000004210 cathodic protection Methods 0.000 description 1
- 239000003518 caustics Substances 0.000 description 1
- 239000011083 cement mortar Substances 0.000 description 1
- QVFWZNCVPCJQOP-UHFFFAOYSA-N chloralodol Chemical compound CC(O)(C)CC(C)OC(O)C(Cl)(Cl)Cl QVFWZNCVPCJQOP-UHFFFAOYSA-N 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000001934 delay Effects 0.000 description 1
- 210000003298 dental enamel Anatomy 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000010301 surface-oxidation reaction Methods 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L58/00—Protection of pipes or pipe fittings against corrosion or incrustation
- F16L58/18—Protection of pipes or pipe fittings against corrosion or incrustation specially adapted for pipe fittings
- F16L58/185—Protection of pipes or pipe fittings against corrosion or incrustation specially adapted for pipe fittings for joints with sleeve or socket
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49826—Assembling or joining
- Y10T29/49885—Assembling or joining with coating before or during assembling
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/4998—Combined manufacture including applying or shaping of fluent material
- Y10T29/49982—Coating
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Protection Of Pipes Against Damage, Friction, And Corrosion (AREA)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
- Rigid Pipes And Flexible Pipes (AREA)
- Branch Pipes, Bends, And The Like (AREA)
- Acyclic And Carbocyclic Compounds In Medicinal Compositions (AREA)
- Buildings Adapted To Withstand Abnormal External Influences (AREA)
Abstract
A method for providing protection against corrosion of a pipe joint (1) formed by the mating of complementary ends (4, 5) of two pipes comprising the steps of: (a) applying controlled heating to a pipe body which is to be joined to an adjacent pipe, (b) applying to the ends (4,5) of each pipe a protective layer or coating of material (2) to the pipe body by a time/temperature func-tion process, (c) allowing the pipe to cool, (d) bevelling the terminations of the protective layer or coating (2), (e) mating comple-mentary ends (4,5) of the pipes together to form a seated and corrosion resistant joint (1).
Description
2 Q ~ S PCr/AU90/ooo55 .~ 1 METHOD OF CORROSION PRO~ cTIoN A5~ PIPE JUNCTIONS
The present invention relates to a method of producing rubber-ring steel jointed~ pipe junctlons having high internal and external long term corrosion protection, tight pipe end-tolerances and being capable of withstanding high operating pressures. Whilst the invention is according to one embodiment directed towards and rrir-ri ly described for producing steel pipe to be used~ in underground pipelines, it is anticipated that the invention is suitable for other iorms of Pir,~l in~.c such as ~ve:lyluulld installations.
Earlier corrosion protection methods for the outer surface of u~lde~yl~und pir~linrc have utilised bit~minn~q enamels, whilst more recently the application of high qualit`y plastic coatings such as polyethylene ( PE ) have been used . Both these methods of corrosion protection have been used in con~unction with cathodic protection systems. Typical prior art corrosion protection methods also utilise epoxy or cement linings for the internal surface of :the steel pipe. - --rr~ro~inr~ ~protection utilising roatin~c such a`s bituminous coatings have the ma~or disadvantage that they create``an effect known as the ~ area ef f ect ' resulting in accelerated local corrosion if the coating is damaged. This often occurs as a result of ~hr;~cinn or-impact during laying of pipes.
~ rn~ l ly~ a weak point in a -rirF~l inr occurs at the junction of pipes- due to the fact- that it-is a site where the n~r~ss~<ry el~ ~ to create~electrolytic corrosion are~
present. It is critical that pipe-~oints be provided with effective resistance against corrosion however, in the past this has proved to be ~ ~ f f i rll 1 t .
At pipe ~oints it is necessary to provide means for the purpose of preventing ingress of moisture which may precipitate corrosive processes. Furth~ ~, it is n~ceCcAry to provide means to prevent the setting up of any electrolytic corrosion proce8s. Pipe ~oints typically comprise the mating of a socket end ( female part) and a spigot end (male part) .
The socket end preferably has an internal qroove into which a rubber ring fits to effect sealing of the ~oint. ~L
~, Typically, the rubber-ring socket end of the pipe has previously been uncoated causing further major problems associated with use of the above-mentioned corrosion protection methods. The failure of such pipes resulting from corrosion of the pipe ends arises ~rom the ingress of moisture and corrosive agents at the pipe joint.
In order to U\~e~ the problems associated with the corrosion of pipe ends, the use of plastic coatings on the outer surface of the pipe has been extended to cover the internal surface of the rubber ring socket end of the pipe.
Even though such practice has marginally improved the corrosion protection for such pipes the known methods of producing rubber ring socket ended steel pipe have not been adequate for producing economical and easy to assemble pipe having the outer plastic coating extending to the internal surface of the pipe joint. The major drawbacks stem from the critical tolerances required for the efficient mating of the pipe joint such that high operating ~t:s=~u, as may be withstood and the increased difficulty associated with laying pir-,l inc~c having the plastic coating extending to the internal surface of the pipe joint.
The present invention seeks to ameliorate the problems associated with rubber ring socket end joint pipes which have previously utilised an outer plastic coating which extends from the outer surface around the socket end to the inner surface of the socket end. The present invention therefore seeks to provide a method for forming a coated pipe junction of two pipes having a spigot end married to a socket P~
_ 3 _ 2o45685 end, each of said pipe ends having its outer surface covered with a protective layer, which extends around the socket end providing protection to the inner surface of the 60cket end.
In one broad form according to the present invention there is provided a method for providing an extended length of corro6ion resistant steel pipe, said length of pipe being formed by the mating of a socket end of a first pipe, with a complementary 6pigot end of a second pipe, said first pipe and said second pipe each having an inner and an outer surface, said method comprising the steps of:
(a) applying controlled heating to said first pipe which is to be joined to said second pipe;
(b) applying to the spigot end and socket end of each pipe an outer protective layer of a plastic, said protective layer having one of its ends terminating on the outer surface of the pipe and the other end terminating on the inner surface of the pipe such that the protective layer covers a portion of the outer surface of each pipe and passes continuously around to the internal surface of each pipe;
(c) heating the plastic coated pipe to eliminate protective layer porosity;
(d) allowing each pipe to cool;
(e) bevelling the plastic protective layer of each pipe;
and (f) inserting the spigot end of said E;econd pipe into the socket end of ~aid ~irst pipe to form a sealed corrosion-resistant joint.
According to another aspect of the present invention there is provided a method for producing protective coating for steel pipes applied at a spigot end and socket end of each pipe 50 that the coating covers a portion of the outer surface of each pipe and passes continuously around the pipe extremitles and along the internal surface of each pipe for a predetermined di3tance thereby providing a corrosion reaistant joint formed by mating of the 6pigot end of one pipe with the socket end of another pipe, the method compri6ing the steps of:
(a) hot rolling a pipe at a first temperature while the pipe is held by at least a first clamp at a distance from gaid socket end with the area of the pipe at or near said f irst clamp being held at a second temperature;
(b) qt]~n~ h i n~ the socket end when said socket end has cooled to a third temperature;
(c) grit blasting simultaneously the pipe outer 6urface and inner surface near the pipe ends in a blast machine;
(d) heating the pipe followed by qu~nl-hing;
(e) immersing the pipe into a protective coating material and rotating the pipe to coat it with a layer of protective coating material;
(f) eliminating the protective layer porosity by infrared radiation heating or by induction heating;
- 4a -(g) cooling the pipe by natural or fan assisted drafting; and (h) bevelling the coating terminations of the protective layer .
In the preferred ~n~hQ~l;r--~ the pipe coating covers the outer surface and inner surface at the pipe ends so that the coating on the inner surface is at least partially sandwiched between the internal pipe surface and a concrete lining. A rubber ring i5 then inserted in a groove after application of a lubricant in the pipe end to provide a seal between it and a mating pipe.
The process i8 intended to be completed in the factory 50 no further field attention to the joint is required .
The invention will now be described by way of example with reference to the ~ -nying drawings in which:
Figure 1 illustrates one ~ i -nt of the cross-section of the socket ended pipe joint prior to assembly .
Figure 2 illustrates the same ~mho~ nt of Figure 1 fully assembled.
The present invention relates to an improved method for producing rubber-ring steel jointed pipe as shown according to one ~ - ' i L in Figures 1 and 2 .
Referring to figures 1 and 2, two views of a cross-section of the pipe j oint are shown, the f irst view showing the ~ oint prior to assembly and the second following assembly. The pipes -WO 90/09542 PCr/AU90/00055 - ~ ~ 5 ~ 20~685 ends have the coating disposed on their external and internal surf aces as shown .
The pipes are coated externally by a polyethylene coating 2 and internally lined by a cement 00rtar lining 3, with the polyethylene coating 2 and cement mortar lining 3 being provided as corrosion resistant h;-rri~r~i for the steel pipes 1. The spigot end 4 of one pipe- may be joined to the socket end 5 of another pipe 1. The socket end 5 is provided with an internal recess located at position 6 to Ar~ te a rubber ring 8. The rubber-ring 8 is lubricated prior to assembly to assist in asse0bly of the joint and provides a compressive -water-tight seal.
( The polyethylene coating 2 extends around the socket 5 end and cnnfin~c internally. The socket S end has its inner surface coated with the polyethylene coating 2 along its length and meets thetcement mortar -lining 3 which protects- the .~ ining internal length of the pipe 1.
The methn~inlogy of the present invention seeks to i0prove the production of :rubber-ring steel ~ointed pipes ab lnnF-d above . -Joint formation is effected in the following manner. !
The pipe is pro~ ned initially with the spigot end of the shell to nominal - dia0eters and hAn l ~ A l l y sized to mate the socket within + 0.50m and limiting the growth at a point, 1200m from the end of jthe:shell. ~ collapse~of~ 1 plate ~hiekn~c5 is ~( introduced at the very end of thc spigot to permit èase 0f -- ~
entry into the socket during asse0bly.
Larger growth values will cause assembly ~1 i f f i n-- 1 ties in the field that could render the ~oint i0possible to assemble.
Diameters below nominal will reduce rubber pre-compression which provide the initial~seal, controls organic root penetration through the joint, provides rounding forces on the socket to reduce lorA ~ i ~ed lip gaps to below the critical level of 2 mm, and therefore eli0inates the ohance of rubber ring blow-out .
The diametric di0ensions of the socket for each specific pipe size are de5igned taking into account the final nominal outside diameter of the spigot and the ~hi~-kn~cs and tolerance _, ,_ WO 90/09542 2 0 4 ~ ~ g ~ PCI /AU90/00055 ;r of the corrosion protection coating. The socket is hot rolled and this demands precise rolling die dimensions and settings plus an accurately controlled pipe t, tllre of 780 C + 20 C
for ~ r;hi 1 ity of socket formation. O
Since the pipe i8 held in clamps approx. 250 mm from the end that will be rolled into a socket, it is imperative that the 780 C + 20 C temperature be uniform and limited in length to 200 mm with a- sudden t<_...~C:LCLULI~ ~r~ nt over the next 50 mm so that the pipe t~ aLuL~: in the clamp area is held at 400 C, max. This will avoid unacceptable shell deformation during the rolling operation.
q~he rate of socket material upset must be controlled to 6 mm per rolling head revolutlon to ensure ~:c,.lc~ :l,Llicity 'o'f rolled socket with the pipe body. The socket formation must be completed in 4 + 1 revolutir~n~ of the rotary~head followed by a controlled llnlr,~lin~ speed of the inner die to-ensure socket roundness and dimensional accuracy.
After the~ completion of . rolling the next step is to 'quench the pipe. While- the pipe ,is still held ~ C~ LlC and round to + 0.5 mm by two clamps (relieved by 1.259~ (outer) and 1.00%~
(inner) to match the ~t' ~~ CLul~ ~r~ nt ~of the shell],~the newly rolled socket,is water quenched and shrunk to-',`~size.' Q~ nrhing~begins-when.the,pipe-~temperature is -approx. 450 C +
2 5 C . 1! ~ . ~ .. . 5:1, ; . , _ , ~ . Where sockets~are-rolled outside sr~orifir~tion`, they-can be corrected as ~.follows ~
When llnfi-~r~ d~ the correction is carried out by partial re-rolling after reheating the socket to 7596 of the standard rolling t~ lCLul~. - ,Great care is required ~when repositioning the already rolled-socket~into-the die system. '' The hump must be centred evenly between the outer dies before c -~in~ to re-roll .
Oversized product is corrected by reheating the socket to 500 C t 2~ C, reclamping and shrinking to size by water qn~nrh i n5 .
, WO 90/09~4~ PCr/AU90/OOOS5 ~ 7 ~ 2~ 68~
SuRFAcE pRRPARA'PION
The neYt step in the proce3s is to prepare the pipe surface in order to enable app1 irAtir~n of the corrosion protection layer. Sound adhesion between the corrosion protection layer and the substrate is obtained rrinrirAl~y due to "Anchor pattern" effects. Optimum pattern conditions are achieved by the use of steel grit abrasive conforming to "running mixes ~ of the following graduation:
mM pA~q~ n~
840 12 . 896 710 27 . 096 600 28.59~
( 500 14 . 596 425 9.296 355 4 . 7%
300 3 . 39 , - - TAREOUT SIZE 177 As 1627 Part 4 Class 2.5 - 3 with profile height of 50 -75 um Rtm and 85 - 95-Rt. - , -~
, The internal s~fAr~c of,~the ~oint ends are~prepared simultAn~o~qly with the - ~t~rnA l ~ process by selective ' rotationalftravel,delays when the rr;t;rA1 ~oint areas are located in the ~ ot Spot" region of the blast- machine. Both direct and reflective particle imr;n,3 ' maintains~profile character~in the socket region~ including~the shadow fa'ces.
~IEATING ~
The next step is to heat the pipe to the correct temperature, gradient prior to coating the pipe with the protective layer.
Direct propane flame imr;n; L heating with additional and i nrl~L~.-n~ open flame end heaters are located at 6 o ' clock providing energy at l50, 000 lW/m . Pipe rotation of 7 - 12 m/min is used during this heat cycle which varies from 4 - 15 min and i8 if'r~ nt on the pipe mass. Temperature gradients are controlled such that 1 - 2 m of the pipe ends are held at 40 + 5 C above the pipe body temperature but never f~r~e~; ng 400 C, at the time of discharge from the oven.
"
WO 90/09542 PCI/AU90/0005~ ~
~ - 8 - 2~6~5 To balance the pipe end cooling effects, the pipe socket end t., Lul~ must be held to 30 + 5 C above the pipe body temperature with a maximum of 345 C, when the pipe dipping ' operation commences. j,~
The spigot end can be held at a t~ Lure closer to the pipe body temperature as there is less internal coating applied i, at that end., For sound ~hl~s i on to be obtained, it is critical that the above t ~- aLuL~ controls and the following lower limits on dip temperature are strictly o~served:
280 C and 10 mm w.t.
300 C 6 mm w . t . ~ `
320 C 5 mm w . t .
340 C 4.5 mm w.t.
~n~
The coating process step which is, a time/temperature f unction f ollows .
The pipe is rotated at 5 - 10 m/min., while- immersed to 30~ of ~ its,-, diameter in a fluidized polyethylene bath, held at 25 - 60 C. E~igher t~, ~Lule~ increase the rate of fusion onto the pipe . T i on times -vary between Z . 5 - 5 min . which provides the-nprpcfi~ry time to deposit coating thi~knP~es.s POST T~A'l~TN(~ ~ ^ s ~
The,,porosity in- the~coating is eliminated in a further step by post heating using inf rared radiation techniques ' i , varying in time- from 5-- 20 min. with the pipe shell t, ~L-,re being held between 180 - 220 C.~ Radiation levels are held at a point where shell temperature will not decay more than 1 C/min . and may even rise at a nominal rate of 0 . 3 C/min .
The socket lining is treated in a similar manner internally except when shell thi~knP~f:es are S mm. In this case induction heating is,re~orted to, using the following conditions:
The induction heating unit operates at 25 kw with 10 k~z frequency and is ON for a number of seconds for five pipe revolution and OFF for number of seconds for one pipe _, .
WO 90/09542 PCI /AU90~00055 - - 9 - 2~685 revolutions to hold shell temperatures at 230 C + 20 C.
Parameters are:
10 mm W.T. Post heat not required.
10 mm W.T. Marginal post heat required.
10 mm W.T. Post heat at 180 - 210 C
Eleating limit is below the onset of surface oxidation and crazing. Temperature measuL~ c of coating surface at e =
0 .96 .
COOLING
Cooling of the pipe is the neYt step and is carried out by natural or fan assisted drafting which lowers the t~, LUL~ from 200 C + 20 C to 60 C within a time limit of not less than 60 minutes. ~ ~
BI~FFING
Buf f bevelling of the coating terminations at 1: 5 tapers follows the cooling step. ~ - -R~ RF.12 R Tl~
- Rubber Fings - of a suitable type are utilised for the` ~
sealing~means of, the pipe ~oint.
The present lnvention thel~:ivl~ provides a method for ~~
producing corrosion barrier coated pipes.
It should be obvious to person~ skilled in the art that numerous-Yariations and modifications could-be made to the method and apparatus of the present inventions as described and with r~f~rF~nre-to, the drawings ~ithout departLng from the ~ve~ cope ~ p~ th~ _t1on, ~.
The present invention relates to a method of producing rubber-ring steel jointed~ pipe junctlons having high internal and external long term corrosion protection, tight pipe end-tolerances and being capable of withstanding high operating pressures. Whilst the invention is according to one embodiment directed towards and rrir-ri ly described for producing steel pipe to be used~ in underground pipelines, it is anticipated that the invention is suitable for other iorms of Pir,~l in~.c such as ~ve:lyluulld installations.
Earlier corrosion protection methods for the outer surface of u~lde~yl~und pir~linrc have utilised bit~minn~q enamels, whilst more recently the application of high qualit`y plastic coatings such as polyethylene ( PE ) have been used . Both these methods of corrosion protection have been used in con~unction with cathodic protection systems. Typical prior art corrosion protection methods also utilise epoxy or cement linings for the internal surface of :the steel pipe. - --rr~ro~inr~ ~protection utilising roatin~c such a`s bituminous coatings have the ma~or disadvantage that they create``an effect known as the ~ area ef f ect ' resulting in accelerated local corrosion if the coating is damaged. This often occurs as a result of ~hr;~cinn or-impact during laying of pipes.
~ rn~ l ly~ a weak point in a -rirF~l inr occurs at the junction of pipes- due to the fact- that it-is a site where the n~r~ss~<ry el~ ~ to create~electrolytic corrosion are~
present. It is critical that pipe-~oints be provided with effective resistance against corrosion however, in the past this has proved to be ~ ~ f f i rll 1 t .
At pipe ~oints it is necessary to provide means for the purpose of preventing ingress of moisture which may precipitate corrosive processes. Furth~ ~, it is n~ceCcAry to provide means to prevent the setting up of any electrolytic corrosion proce8s. Pipe ~oints typically comprise the mating of a socket end ( female part) and a spigot end (male part) .
The socket end preferably has an internal qroove into which a rubber ring fits to effect sealing of the ~oint. ~L
~, Typically, the rubber-ring socket end of the pipe has previously been uncoated causing further major problems associated with use of the above-mentioned corrosion protection methods. The failure of such pipes resulting from corrosion of the pipe ends arises ~rom the ingress of moisture and corrosive agents at the pipe joint.
In order to U\~e~ the problems associated with the corrosion of pipe ends, the use of plastic coatings on the outer surface of the pipe has been extended to cover the internal surface of the rubber ring socket end of the pipe.
Even though such practice has marginally improved the corrosion protection for such pipes the known methods of producing rubber ring socket ended steel pipe have not been adequate for producing economical and easy to assemble pipe having the outer plastic coating extending to the internal surface of the pipe joint. The major drawbacks stem from the critical tolerances required for the efficient mating of the pipe joint such that high operating ~t:s=~u, as may be withstood and the increased difficulty associated with laying pir-,l inc~c having the plastic coating extending to the internal surface of the pipe joint.
The present invention seeks to ameliorate the problems associated with rubber ring socket end joint pipes which have previously utilised an outer plastic coating which extends from the outer surface around the socket end to the inner surface of the socket end. The present invention therefore seeks to provide a method for forming a coated pipe junction of two pipes having a spigot end married to a socket P~
_ 3 _ 2o45685 end, each of said pipe ends having its outer surface covered with a protective layer, which extends around the socket end providing protection to the inner surface of the 60cket end.
In one broad form according to the present invention there is provided a method for providing an extended length of corro6ion resistant steel pipe, said length of pipe being formed by the mating of a socket end of a first pipe, with a complementary 6pigot end of a second pipe, said first pipe and said second pipe each having an inner and an outer surface, said method comprising the steps of:
(a) applying controlled heating to said first pipe which is to be joined to said second pipe;
(b) applying to the spigot end and socket end of each pipe an outer protective layer of a plastic, said protective layer having one of its ends terminating on the outer surface of the pipe and the other end terminating on the inner surface of the pipe such that the protective layer covers a portion of the outer surface of each pipe and passes continuously around to the internal surface of each pipe;
(c) heating the plastic coated pipe to eliminate protective layer porosity;
(d) allowing each pipe to cool;
(e) bevelling the plastic protective layer of each pipe;
and (f) inserting the spigot end of said E;econd pipe into the socket end of ~aid ~irst pipe to form a sealed corrosion-resistant joint.
According to another aspect of the present invention there is provided a method for producing protective coating for steel pipes applied at a spigot end and socket end of each pipe 50 that the coating covers a portion of the outer surface of each pipe and passes continuously around the pipe extremitles and along the internal surface of each pipe for a predetermined di3tance thereby providing a corrosion reaistant joint formed by mating of the 6pigot end of one pipe with the socket end of another pipe, the method compri6ing the steps of:
(a) hot rolling a pipe at a first temperature while the pipe is held by at least a first clamp at a distance from gaid socket end with the area of the pipe at or near said f irst clamp being held at a second temperature;
(b) qt]~n~ h i n~ the socket end when said socket end has cooled to a third temperature;
(c) grit blasting simultaneously the pipe outer 6urface and inner surface near the pipe ends in a blast machine;
(d) heating the pipe followed by qu~nl-hing;
(e) immersing the pipe into a protective coating material and rotating the pipe to coat it with a layer of protective coating material;
(f) eliminating the protective layer porosity by infrared radiation heating or by induction heating;
- 4a -(g) cooling the pipe by natural or fan assisted drafting; and (h) bevelling the coating terminations of the protective layer .
In the preferred ~n~hQ~l;r--~ the pipe coating covers the outer surface and inner surface at the pipe ends so that the coating on the inner surface is at least partially sandwiched between the internal pipe surface and a concrete lining. A rubber ring i5 then inserted in a groove after application of a lubricant in the pipe end to provide a seal between it and a mating pipe.
The process i8 intended to be completed in the factory 50 no further field attention to the joint is required .
The invention will now be described by way of example with reference to the ~ -nying drawings in which:
Figure 1 illustrates one ~ i -nt of the cross-section of the socket ended pipe joint prior to assembly .
Figure 2 illustrates the same ~mho~ nt of Figure 1 fully assembled.
The present invention relates to an improved method for producing rubber-ring steel jointed pipe as shown according to one ~ - ' i L in Figures 1 and 2 .
Referring to figures 1 and 2, two views of a cross-section of the pipe j oint are shown, the f irst view showing the ~ oint prior to assembly and the second following assembly. The pipes -WO 90/09542 PCr/AU90/00055 - ~ ~ 5 ~ 20~685 ends have the coating disposed on their external and internal surf aces as shown .
The pipes are coated externally by a polyethylene coating 2 and internally lined by a cement 00rtar lining 3, with the polyethylene coating 2 and cement mortar lining 3 being provided as corrosion resistant h;-rri~r~i for the steel pipes 1. The spigot end 4 of one pipe- may be joined to the socket end 5 of another pipe 1. The socket end 5 is provided with an internal recess located at position 6 to Ar~ te a rubber ring 8. The rubber-ring 8 is lubricated prior to assembly to assist in asse0bly of the joint and provides a compressive -water-tight seal.
( The polyethylene coating 2 extends around the socket 5 end and cnnfin~c internally. The socket S end has its inner surface coated with the polyethylene coating 2 along its length and meets thetcement mortar -lining 3 which protects- the .~ ining internal length of the pipe 1.
The methn~inlogy of the present invention seeks to i0prove the production of :rubber-ring steel ~ointed pipes ab lnnF-d above . -Joint formation is effected in the following manner. !
The pipe is pro~ ned initially with the spigot end of the shell to nominal - dia0eters and hAn l ~ A l l y sized to mate the socket within + 0.50m and limiting the growth at a point, 1200m from the end of jthe:shell. ~ collapse~of~ 1 plate ~hiekn~c5 is ~( introduced at the very end of thc spigot to permit èase 0f -- ~
entry into the socket during asse0bly.
Larger growth values will cause assembly ~1 i f f i n-- 1 ties in the field that could render the ~oint i0possible to assemble.
Diameters below nominal will reduce rubber pre-compression which provide the initial~seal, controls organic root penetration through the joint, provides rounding forces on the socket to reduce lorA ~ i ~ed lip gaps to below the critical level of 2 mm, and therefore eli0inates the ohance of rubber ring blow-out .
The diametric di0ensions of the socket for each specific pipe size are de5igned taking into account the final nominal outside diameter of the spigot and the ~hi~-kn~cs and tolerance _, ,_ WO 90/09542 2 0 4 ~ ~ g ~ PCI /AU90/00055 ;r of the corrosion protection coating. The socket is hot rolled and this demands precise rolling die dimensions and settings plus an accurately controlled pipe t, tllre of 780 C + 20 C
for ~ r;hi 1 ity of socket formation. O
Since the pipe i8 held in clamps approx. 250 mm from the end that will be rolled into a socket, it is imperative that the 780 C + 20 C temperature be uniform and limited in length to 200 mm with a- sudden t<_...~C:LCLULI~ ~r~ nt over the next 50 mm so that the pipe t~ aLuL~: in the clamp area is held at 400 C, max. This will avoid unacceptable shell deformation during the rolling operation.
q~he rate of socket material upset must be controlled to 6 mm per rolling head revolutlon to ensure ~:c,.lc~ :l,Llicity 'o'f rolled socket with the pipe body. The socket formation must be completed in 4 + 1 revolutir~n~ of the rotary~head followed by a controlled llnlr,~lin~ speed of the inner die to-ensure socket roundness and dimensional accuracy.
After the~ completion of . rolling the next step is to 'quench the pipe. While- the pipe ,is still held ~ C~ LlC and round to + 0.5 mm by two clamps (relieved by 1.259~ (outer) and 1.00%~
(inner) to match the ~t' ~~ CLul~ ~r~ nt ~of the shell],~the newly rolled socket,is water quenched and shrunk to-',`~size.' Q~ nrhing~begins-when.the,pipe-~temperature is -approx. 450 C +
2 5 C . 1! ~ . ~ .. . 5:1, ; . , _ , ~ . Where sockets~are-rolled outside sr~orifir~tion`, they-can be corrected as ~.follows ~
When llnfi-~r~ d~ the correction is carried out by partial re-rolling after reheating the socket to 7596 of the standard rolling t~ lCLul~. - ,Great care is required ~when repositioning the already rolled-socket~into-the die system. '' The hump must be centred evenly between the outer dies before c -~in~ to re-roll .
Oversized product is corrected by reheating the socket to 500 C t 2~ C, reclamping and shrinking to size by water qn~nrh i n5 .
, WO 90/09~4~ PCr/AU90/OOOS5 ~ 7 ~ 2~ 68~
SuRFAcE pRRPARA'PION
The neYt step in the proce3s is to prepare the pipe surface in order to enable app1 irAtir~n of the corrosion protection layer. Sound adhesion between the corrosion protection layer and the substrate is obtained rrinrirAl~y due to "Anchor pattern" effects. Optimum pattern conditions are achieved by the use of steel grit abrasive conforming to "running mixes ~ of the following graduation:
mM pA~q~ n~
840 12 . 896 710 27 . 096 600 28.59~
( 500 14 . 596 425 9.296 355 4 . 7%
300 3 . 39 , - - TAREOUT SIZE 177 As 1627 Part 4 Class 2.5 - 3 with profile height of 50 -75 um Rtm and 85 - 95-Rt. - , -~
, The internal s~fAr~c of,~the ~oint ends are~prepared simultAn~o~qly with the - ~t~rnA l ~ process by selective ' rotationalftravel,delays when the rr;t;rA1 ~oint areas are located in the ~ ot Spot" region of the blast- machine. Both direct and reflective particle imr;n,3 ' maintains~profile character~in the socket region~ including~the shadow fa'ces.
~IEATING ~
The next step is to heat the pipe to the correct temperature, gradient prior to coating the pipe with the protective layer.
Direct propane flame imr;n; L heating with additional and i nrl~L~.-n~ open flame end heaters are located at 6 o ' clock providing energy at l50, 000 lW/m . Pipe rotation of 7 - 12 m/min is used during this heat cycle which varies from 4 - 15 min and i8 if'r~ nt on the pipe mass. Temperature gradients are controlled such that 1 - 2 m of the pipe ends are held at 40 + 5 C above the pipe body temperature but never f~r~e~; ng 400 C, at the time of discharge from the oven.
"
WO 90/09542 PCI/AU90/0005~ ~
~ - 8 - 2~6~5 To balance the pipe end cooling effects, the pipe socket end t., Lul~ must be held to 30 + 5 C above the pipe body temperature with a maximum of 345 C, when the pipe dipping ' operation commences. j,~
The spigot end can be held at a t~ Lure closer to the pipe body temperature as there is less internal coating applied i, at that end., For sound ~hl~s i on to be obtained, it is critical that the above t ~- aLuL~ controls and the following lower limits on dip temperature are strictly o~served:
280 C and 10 mm w.t.
300 C 6 mm w . t . ~ `
320 C 5 mm w . t .
340 C 4.5 mm w.t.
~n~
The coating process step which is, a time/temperature f unction f ollows .
The pipe is rotated at 5 - 10 m/min., while- immersed to 30~ of ~ its,-, diameter in a fluidized polyethylene bath, held at 25 - 60 C. E~igher t~, ~Lule~ increase the rate of fusion onto the pipe . T i on times -vary between Z . 5 - 5 min . which provides the-nprpcfi~ry time to deposit coating thi~knP~es.s POST T~A'l~TN(~ ~ ^ s ~
The,,porosity in- the~coating is eliminated in a further step by post heating using inf rared radiation techniques ' i , varying in time- from 5-- 20 min. with the pipe shell t, ~L-,re being held between 180 - 220 C.~ Radiation levels are held at a point where shell temperature will not decay more than 1 C/min . and may even rise at a nominal rate of 0 . 3 C/min .
The socket lining is treated in a similar manner internally except when shell thi~knP~f:es are S mm. In this case induction heating is,re~orted to, using the following conditions:
The induction heating unit operates at 25 kw with 10 k~z frequency and is ON for a number of seconds for five pipe revolution and OFF for number of seconds for one pipe _, .
WO 90/09542 PCI /AU90~00055 - - 9 - 2~685 revolutions to hold shell temperatures at 230 C + 20 C.
Parameters are:
10 mm W.T. Post heat not required.
10 mm W.T. Marginal post heat required.
10 mm W.T. Post heat at 180 - 210 C
Eleating limit is below the onset of surface oxidation and crazing. Temperature measuL~ c of coating surface at e =
0 .96 .
COOLING
Cooling of the pipe is the neYt step and is carried out by natural or fan assisted drafting which lowers the t~, LUL~ from 200 C + 20 C to 60 C within a time limit of not less than 60 minutes. ~ ~
BI~FFING
Buf f bevelling of the coating terminations at 1: 5 tapers follows the cooling step. ~ - -R~ RF.12 R Tl~
- Rubber Fings - of a suitable type are utilised for the` ~
sealing~means of, the pipe ~oint.
The present lnvention thel~:ivl~ provides a method for ~~
producing corrosion barrier coated pipes.
It should be obvious to person~ skilled in the art that numerous-Yariations and modifications could-be made to the method and apparatus of the present inventions as described and with r~f~rF~nre-to, the drawings ~ithout departLng from the ~ve~ cope ~ p~ th~ _t1on, ~.
Claims (20)
1. A method for providing an extended length of corrosion resistant steel pipe, said length of pipe being formed by the mating of a socket end of a first pipe, with a complementary spigot end of a second pipe, said first pipe and said second pipe each having an inner and an outer surface, said method comprising the steps of:
(a) applying controlled heating to said first pipe which is to be joined to said second pipe;
(b) applying to the spigot end and socket end of each pipe an outer protective layer of a plastic, said protective layer having one of its ends terminating on the outer surface of the pipe and the other end terminating on the inner surface of the pipe such that the protective layer covers a portion of the outer surface of each pipe and passes continuously around to the internal surface of each pipe;
(c) heating the plastic coated pipe to eliminate protective layer porosity;
(d) allowing each pipe to cool;
(e) bevelling the plastic protective layer of each pipe; and (f) inserting the spigot end of said second pipe into the socket end of said first pipe to form a sealed corrosion-resistant joint.
(a) applying controlled heating to said first pipe which is to be joined to said second pipe;
(b) applying to the spigot end and socket end of each pipe an outer protective layer of a plastic, said protective layer having one of its ends terminating on the outer surface of the pipe and the other end terminating on the inner surface of the pipe such that the protective layer covers a portion of the outer surface of each pipe and passes continuously around to the internal surface of each pipe;
(c) heating the plastic coated pipe to eliminate protective layer porosity;
(d) allowing each pipe to cool;
(e) bevelling the plastic protective layer of each pipe; and (f) inserting the spigot end of said second pipe into the socket end of said first pipe to form a sealed corrosion-resistant joint.
2. The method according to claim 1 comprising the additional preliminary steps before controlled heating of the first pipe of:
(a) hot rolling the first pipe at a first temperature while the first pipe is held by at least one clamp;
(b) quenching the socket end of the first pipe when the socket end has cooled to a second temperature.
(a) hot rolling the first pipe at a first temperature while the first pipe is held by at least one clamp;
(b) quenching the socket end of the first pipe when the socket end has cooled to a second temperature.
3. The method according to claim 2 further comprising the step of grit blasting the outer surface and the inner surface of each pipe near the pipe ends prior tocontrolled heating of the first and second pipes.
4. The method according to claim 3 further comprising the step of reheating the pipe socket end after said quenching, and then rerolling the pipe to increase the size of the pipe socket end.
5. The method according to claim 3 further comprising the step of reheating the socket end after said quenching, then clamping and heating followed by quenching the pipe socket end to reduce its size.
6. The method according to claim 5 wherein said reheating of the socket end is to a temperature within the range of 475° C to 525° C.
7. The method according to claim 2 wherein the hot rolling temperature is controlled within the range of 760° C to 800° C. and at a distance not greater than 250 mm from the heated pipe end.
8. The method according to claim 7 wherein the pipe temperature in the clamp area is not greater than 400° C.
9. The method according to claim 8 wherein the quenching begins when said second temperature is within the range of 425° C 475° C.
10. The method according to claim 1 wherein said plastic protective layer is applied by immersing the pipe end in the protective layer material and rotating the pipe.
11. The method according to claim 10 wherein said eliminating of protective layer porosity is by infrared radiation or by induction heating.
12. The method according to claim 10 wherein said controlled heating of the first pipe comprises rotating the pipe in an open flame.
13. The method according to claim 1 wherein said heating to eliminate protectivelayer porosity comprises infrared radiation for a period of 5 to 20 minutes and at a temperature falling within the range of 180°C to 220°C.
14. A method for producing protective coating for steel pipes applied at a spigot end and socket end of each pipe so that the coating covers a portion of the outer surface of each pipe and passes continuously around the pipe extremities and along the internal surface of each pipe for a predetermined distance thereby providing a corrosion resistant joint formed by mating of the spigot end of one pipe with the socket end of another pipe, the method comprising the steps of:
(a) hot rolling a pipe at a first temperature while the pipe is held by at least a first clamp at a distance from said socket end with the area of the pipe at or near said first clamp being held at a second temperature;
(b) quenching the socket end when said socket end has cooled to a third temperature;
(c) grit blasting simultaneously the pipe outer surface and inner surface near the pipe ends in a blast machine;
(d) heating the pipe followed by quenching;
(e) immersing the pipe into a protective coating material and rotating the pipe to coat it with a layer of protective coating material;
(f) eliminating the protective layer porosity by infrared radiation heating or by induction heating;
(g) cooling the pipe by natural or fan assisted drafting; and (h) bevelling the coating terminations of the protective layer.
(a) hot rolling a pipe at a first temperature while the pipe is held by at least a first clamp at a distance from said socket end with the area of the pipe at or near said first clamp being held at a second temperature;
(b) quenching the socket end when said socket end has cooled to a third temperature;
(c) grit blasting simultaneously the pipe outer surface and inner surface near the pipe ends in a blast machine;
(d) heating the pipe followed by quenching;
(e) immersing the pipe into a protective coating material and rotating the pipe to coat it with a layer of protective coating material;
(f) eliminating the protective layer porosity by infrared radiation heating or by induction heating;
(g) cooling the pipe by natural or fan assisted drafting; and (h) bevelling the coating terminations of the protective layer.
15. The method according to claim 14 wherein the hot rolling temperature is controlled within the range of 760° C. to 800° C. at a distance not greater than 250 mm from the heated pipe end.
16. The method according to claim 15 wherein said second temperature is not greater than 400° C.
17. The method according to claim 16 wherein the quenching begins when said third temperature is within the range of 425° C ho 475° C.
18. The method according to claim 17 wherein after said quenching of the socket end it is reheated to a temperature within the range of 475° C to 525° C.
19. The method according to claim 18 wherein the heating of the pipe before saidimmersion in said protective coating material comprises rotating the pipe in an open flame.
20. The method according to claim 19 wherein said infrared radiation heating takes place for a period of 5 to 20 minutes and at a temperature falling within the range of 180° C. to 220° C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AUPJ2670 | 1989-02-09 | ||
| AUPJ267089 | 1989-02-09 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2045685A1 CA2045685A1 (en) | 1990-08-10 |
| CA2045685C true CA2045685C (en) | 1996-09-17 |
Family
ID=3773702
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002009768A Abandoned CA2009768A1 (en) | 1989-02-09 | 1990-02-09 | Method for corrosion protection at pipe junctions |
| CA002045685A Expired - Lifetime CA2045685C (en) | 1989-02-09 | 1990-02-09 | Method of corrosion protection at pipe junctions |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002009768A Abandoned CA2009768A1 (en) | 1989-02-09 | 1990-02-09 | Method for corrosion protection at pipe junctions |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US5274897A (en) |
| EP (1) | EP0457825B1 (en) |
| AT (1) | ATE120266T1 (en) |
| CA (2) | CA2009768A1 (en) |
| DE (1) | DE69018066T2 (en) |
| ES (1) | ES2069733T3 (en) |
| HK (1) | HK1006744A1 (en) |
| WO (1) | WO1990009542A1 (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3330921B2 (en) * | 2000-03-13 | 2002-10-07 | 菊池プレス工業株式会社 | Tailored blank articles and method for producing the same |
| US7641241B2 (en) * | 2003-11-20 | 2010-01-05 | Tyco Water Pty Limited | Method of corrosion protection at a welded pipe joint and resulting joint |
| AU2004291562B2 (en) * | 2003-11-20 | 2011-01-27 | Steel Mains Pty Ltd | Method of corrosion protection at a welded pipe joint and resulting joint |
| AU2014201808B2 (en) * | 2006-04-12 | 2016-02-04 | Orrcon Operations Pty Ltd | Pipe and pipe joining method |
| SE531990C2 (en) * | 2007-01-29 | 2009-09-22 | Aga Ab | Process for heat treatment of long steel products |
| US8461473B2 (en) * | 2008-10-27 | 2013-06-11 | Wpw, Llc | External corrosion protection for underground pipes |
| US9599258B1 (en) | 2013-10-21 | 2017-03-21 | Butler Tech Corporation | Mechanical pipe joints and methods of forming and sealing the same |
Family Cites Families (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2001204A (en) * | 1934-03-03 | 1935-05-14 | James A Long | Pipe joint and method of making the same |
| FR1145591A (en) * | 1956-03-09 | 1957-10-28 | Cie De Pont A Mousson | Pipe |
| US3020068A (en) * | 1959-02-18 | 1962-02-06 | Victaulic Co Of America | Coupling of lined pipe and methods |
| US3208136A (en) * | 1963-08-16 | 1965-09-28 | Joslin Alvin Earl | Method of joining pipe |
| FR85400E (en) * | 1964-06-26 | 1965-07-30 | Ct De Rech S De Pont A Mousson | Sealing washer for composite pipes and gasket with application |
| CH413720A (en) * | 1964-11-28 | 1966-05-15 | Domenico Ing Domenighetti | Loose material conveyor and lifter, with sliding bucket on rails |
| AT307833B (en) * | 1967-09-09 | 1973-06-12 | Benteler Werke Ag | Thread-free soldered joint for steel pipes and method for producing the same |
| DE1933888A1 (en) * | 1969-07-03 | 1971-01-28 | Nippon Kokan Kk | Method for joining large diameter steel pipes and pieces of pipe for use in this method |
| US3675950A (en) * | 1969-11-21 | 1972-07-11 | Schlumberger Technology Corp | Articles of manufacture including cylindrical members having specially-terminated protective coatings |
| DE2258023A1 (en) * | 1972-11-27 | 1974-05-30 | Berg Roehrenwerk U Behaelterba | PIPE CONNECTION FOR PIPES IN PARTICULAR PROVIDED WITH A PROTECTIVE LAYER |
| US4035003A (en) * | 1974-12-30 | 1977-07-12 | Concrete Pipe Consultants, Inc. | Pipe joint for large diameter flexible pipes |
| US4077098A (en) * | 1975-04-07 | 1978-03-07 | Nippon Steel Corporation | Apparatus for manufacturing a metallic tube coated with a thermoplastic resin film having little residual strain |
| US4182782A (en) * | 1975-09-24 | 1980-01-08 | Metallgesellschaft Aktiengesellschaft | Method of a coating on the outside surface of a metal pipe |
| US4064619A (en) * | 1976-12-03 | 1977-12-27 | Zap-Lok Systems International, Inc. | Method of joining plastic coated pipe |
| IT7850277A0 (en) * | 1977-07-15 | 1978-07-13 | Miami Florida Usa A | PROCEDURE AND MEANS FOR COATING PIPES |
| GB1542333A (en) * | 1977-11-18 | 1979-03-14 | British Steel Corp | Coating of pipes |
| GB2145639A (en) * | 1983-08-25 | 1985-04-03 | Shaw Ind Ltd | Impact-resistant, moisture-impermeable resinous coatings and method of applying the same to an object |
| DE3639417C1 (en) * | 1986-11-18 | 1987-11-26 | Mannesmann Ag | Process for encasing objects made of steel with plastic |
-
1990
- 1990-02-09 AT AT90903307T patent/ATE120266T1/en not_active IP Right Cessation
- 1990-02-09 CA CA002009768A patent/CA2009768A1/en not_active Abandoned
- 1990-02-09 DE DE69018066T patent/DE69018066T2/en not_active Expired - Lifetime
- 1990-02-09 US US07/721,651 patent/US5274897A/en not_active Expired - Lifetime
- 1990-02-09 WO PCT/AU1990/000055 patent/WO1990009542A1/en active IP Right Grant
- 1990-02-09 EP EP90903307A patent/EP0457825B1/en not_active Expired - Lifetime
- 1990-02-09 ES ES90903307T patent/ES2069733T3/en not_active Expired - Lifetime
- 1990-02-09 CA CA002045685A patent/CA2045685C/en not_active Expired - Lifetime
-
1998
- 1998-06-22 HK HK98105922A patent/HK1006744A1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| ES2069733T3 (en) | 1995-05-16 |
| ATE120266T1 (en) | 1995-04-15 |
| US5274897A (en) | 1994-01-04 |
| DE69018066T2 (en) | 1995-07-27 |
| WO1990009542A1 (en) | 1990-08-23 |
| CA2009768A1 (en) | 1990-08-09 |
| EP0457825B1 (en) | 1995-03-22 |
| DE69018066D1 (en) | 1995-04-27 |
| EP0457825A4 (en) | 1992-07-22 |
| EP0457825A1 (en) | 1991-11-27 |
| HK1006744A1 (en) | 1999-03-12 |
| CA2045685A1 (en) | 1990-08-10 |
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| EEER | Examination request | ||
| MKEX | Expiry | ||
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Effective date: 20100209 |